Laboratory equipment



April 6, 1937.v F. E. sTRYsMAN ET AL 2,076,485

LABORATORY EQUIPMENT Filed Dec. 4, 1933 SWZQZ INVENTORSl www THEIRATTORNEYS Patented Apr. 6, 1937 UNITED STATES PATENT OFFICE LABORATORYEQUIPMENT Francis E. Streysman and Michael T. Strikol,

3 Claims.

Our invention relates to laboratory equipment, and includes among itsobjects and advantages an improved electrical heater in the nature of aBunsen burner.

This invention also consists in certain other features of constructionand in the combination and arrangement of the several parts, to behereinafter fully described, illustrated in the accompanying drawing andspecifically pointed out in the appended claims.

In describing our invention in detail, reference will be had to theaccompanying drawing wherein like characters denote like orcorresponding parts throughout the several Views, and in which:

Fig. 1 is a perspective view illustrating our device;

Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is a sectional view taken along the line 3 3 of Fig. 2; and

Fig. 4 is a perspective View of a portion of the device.

In the embodiment selected to illustrate our invention, we make use of asmall table I0 comprising a sheet metal top l2 about five inches squaremounted upon legs I 4. Each leg is provided with a small cushion I5 atits end to prevent scratching of table and desk tops.

A metal cup I8 projects through an opening 20 in the top I2 and isprovided with a flange 22 extending over the top and secured thereto bymeans of screws 24. This cup comprises the'outer wall of an electricfurnace made up of an inner jacket 2t of insulating material, such asporcelain, and resting with its open bottom on a layer 28 of insulatingmaterial, such as asbestos. The asbestos insulating material extendsupwardly between the jacket 26 and the cup 28, as at 30.

Referring to Fig. 3, the inner jacket 26 comprises four separate pieces32, each having an edge groove 34 arranged to receive a tongue 36carried by the adjacent piece. Thus, the parts 32 are effectivelyconnected together when the rectangular assembly is fitted snugly withinthe asbestos walls 3D. Each piece 32 is provided with a flange 38extending over the ends of the asbestos walls 35i and the flange 22. Tworibs 4i) are formed integrally with each piece 32 and are provided withrecesses 42 in their ends arranged to receive a heating element 44 inthe nature of a wire coil. The ends of the heating element are connectedwith terminal screws 46, to which conductors 48, supplying current tothe heating ele- 55 ment, may be fastened. We cut out the asbestosinsulation and the cup I8 at 5@ and 52 to accommodate the electric cord.

The electrical element 44 is wound over one rib and under the next ribto provide a plurality of diagonal reaches 54 surrounding the wall ofthe furnace. The opening defined by the inner jacket is sufficientlylarge to freely receive test tubes of conventional size and design. Itwill be noted that the ribs 4.0 project beyond the heating element 44.This arrangement protects the heating element from being bent or damagedby devices placed within the furnace. The ribs also prevent a directcontact between the test tubes and the heating element, thus protectingthe tube.

A cover 54 is arranged to close the upper end of the furnace and isprovided with a flange 45 fitting snugly about the inner jacket 26. Thiscover is provided with a vent 58 to permit heated air to pass from thefurnace. We provide a draft regulator comprising a closure plate 60slidably retained within supporting flanges 62 welded t0 the jacket I8.This plate is arranged to uncover openings 64 in one wall of the furnacenear its bottom, to provide the necessary draft in the furnace.

In operation, a number of covers 54 may be provided with openings ofdifferent diameters to accommodate devices of different dimensions andto change the nature of the convection current passing from the furnace.Our invention functions as a full equivalent to devices in the nature ofBunsen burners. There are added advantages in that our electrical unitleaves no deposit upon test tubes and devices such as frequently occurwith the use of a name. The closure plate 60 may be operated to vary thedraft to suit different operating conditions. Thus, by adjusting theplate 60 and using a cover 52 with an opening of predetermined diameter,the velocity of the convection current and its operating altitude may beaccurately controlled. We have found that the present device generatessufficient heat to boil liquids in test tubes held at a considerabledistance above the furnace in the path of the convection current. Thedevice is also an ideal unit for heating crucibles which may bepositioned within the furnace. The cover 54 provides an ideal supportfor the crucibles.

It will be understood that heating elements other than a coiled wire maybe employed in lieu of the unit illustrated. We may also provide thedraft openings 64 in the bottom of the furnace instead of its side. Ourpieces 34 comprising the inner jacket 30 are identical in construction,thusl simplifying the construction and o of the same material as theinner jacket.

reducing the cost of manufacture. We prefer to make the inner jacket ina number of parts to eliminate breakage due to expansion and contractionin the material. Our cover 52 is made The unit is light in weight, whichmakes it an ideal portable unit for laboratory work. While we haveillustrated the furnace as being rectangular in cross section, it willbe understood that a cirlO cular design may be used with equaladvantage.

20 ordinary wall outlet sockets, thus eliminating the necessity for aspecial gas conduit as is required in connection with Bunsen burners.Then too,

there are large areas in which gas is not provided so that it isnecessary to employ improvised D devices, such as oil burners andalcohol lamps.

Without further elaboration the foregoing will so fully explain ourinvention that others may, by applying current knowledge, readily adaptthe same for use under various conditions of service.

We claim:

l. A laboratory device comprising a table having legs and an opening inits top, a metal cup positioned within said opening and having a flangeextending over a portion of the table top, means fastening said flangeto said table top, an insulating material jacket lining the inner walland bottom of said cup, an inner Wall of insulating material ttingsnugly within said insulating jacket and having its end extendingslightly above the table top, a flange formed integrally with said wallof insulating material and extending over the top of the insulatingjacket and a portion of said first-named flange, an electrical heatingelement mounted upon supporting lugs projecting inwardly from the innerside of said inner wall, said furnace being provided with a plurality ofdraft openings, and a plate slidably associated with the furnace foropening and closing said draft openings.

50 2. A laboratory device comprising a table having legs and an openingin its top, a metal cup positioned within said opening and having ailange extending over a portion of the table top, means fastening saidflange to said table top, an insulating material jacket lining the innerwall and bottom of said cup, an inner wall of insulating materialfitting snugly within said insulating jacket and having its endextending slightly above the table top, a flange formed integrally withsaid wall of insulating material and extending over the top of theinsulating jacket and a portion of said first-named ange, an electricalheating element mounted upon supporting lugs projecting inwardly fromthe inner side of said inner wall, said furnace being provided with aplurality of draft openings, and a plate slidably associated with thefurnace for opening and closing said draft openings, said inner Wallconiprising a plurality of pieces, and each piece being provided with atongue and a groove arranged to co-operate with the tongue and groove ofa companion piece, to connect the pieces into a unitary structure.

3. A laboratory device comprising a table having legs and an opening inits top, a metal cup positioned within said opening and having a flangeextending over a portion of the table top, means fastening said ange tosaid table top, an insulating material jacket lining the inner wall andbottom of said cup, an inner wall of insulating material fitting snuglywithin said insulating jacket and having its end extending slightlyabove the table top, a flange formed integrally with said wall ofinsulating material and extending over the top of the insulating jacketand a portion of said first-named flange, an electrical L heatingelement mounted upon supporting lugs projecting inwardly from the innerside of said inner wall, said furnace being provided with a plurality ofdraft openings, and a plate slidably associated with the furnace foropening and closing said draft openings, said inner wall comprising aplurality of pieces, and each piece being provided with a tongue and agroove arranged to co-operate with the tongue and groove of a companionpiece, to connect the pieces into a unitary structure, said lugsprojecting beyond the heating element, to provide abutments preventingdirect contact between a device inserted in the furnace and saidelectric element.

FRANCIS E. STREYSMAN. MICHAEL T. STRIKOL.

